It doesn’t sound bizarre in the slightest. You still have a memory of past sins, and it may be that you still feel guilty and maybe that you may still have temptations in that area. Nearly everywhere you go you are going to see a picture of half a naked person, so simply avoiding it, isn’t enough. You have to build up an endurance of thought. Simply seeing a body of a naked person is not a sin, otherwise why has God made us naked? It’s what you do with that imagery; that’s the problem. The devil may come and tempt you with perverse thoughts, these may flash in and out of you mind depending on how strong your endurance of mind is; and this is because you have a pass memory and guilt of sin, and you are paranoid that you are committing the same embarrassing sins you were committing before—sounds like your becoming scrupulous. This still is not a sin. It becomes a sin when you say yes to the thoughts and fully engage in them with your free will. Although bad thoughts might stay in your mind for a while, I believe that you are neutral until you say yes to the perversion that particular thought is provoking you to engage in.
You are paranoid that you are going to those internet sites, while using the excuse of buying underwear, to look at naked bodies; but, this is the devil at work to beat you down in to a position were you going to end up tearing out your eyes because everything you see is going to be a cause of sin. If you are going to the sight to buy underwear, then that is what you are doing, even if you feel tempted by the picture. Obviously, if you know that you will fall in to sin by going to that site, then it would be a sin to go there, but I don’t agree that it is enough to just hide away from temptation. So long as you’re not going to a porno sight, i dont actually see the sin that one is commiting buy buying underwear from a site that just happens to have a model on it. It may be that i am wrong(and im sorry if i am), but how will you become stronger in the spirit, if we are going to close are eyes every time a bit of flesh is revealed to them?(I think that this will actually increase the temptation!). But if you dont have to go to such a site, then don’t.
It’s not the naked flesh that’s the problem; its how your mind perceives that flesh, that’s the problem. It’s an internal problem you have, not the internet site that you are going to. Additionally I would say that if you feel uncomfortable about going to a particular site because you know that there is a naked body there, then go to another one; but don’t become embarrassed or guilty or paranoid, just because a naked body pops up on the screen unavoidably, or because you feel attracted to that body. You cannot over-come sin that way, you have to take it on by seeing the flesh for what it really is, rather then what our perverted hearts have twisted them into. In order to do this, you have to walk the paths of the saints, you have to build up a spiritual endurance, other wise when you do get put in to a situation of temptation, it will be so over whelming, you might as well cut your eyes out, and while you’re at it, cut you hand of as well if it offends God! I don’t think any of us would want to literally do that!
Peace and God bless.